The primary objective of this study is to determine whether dimethyl fumarate (DMF) taken over 12 months is effective in reducing Multiple Sclerosis (MS)-related fatigue, as measured by mean changes in the Fatigue Scale for Motor and Cognitive Functions (FSMC), in participants with relapsing-remitting multiple sclerosis (RRMS). The secondary objectives of this study are: To investigate changes from Baseline in FSMC and fatigue severity (Fatigue Severity Scale [FSS]) at 1, 3, 6, 9, and 12 months in participants receiving DMF; To assess the impact of DMF on patient-reported outcomes (PROs), including work productivity (Work Productivity and Activity Impairment-Multiple Sclerosis questionnaire [WPAI-MS]), health-related quality of life (Short Form Health Survey [SF-12]), depression (Beck Depression Inventory-Fast Screen [BDI-FS]), and sleepiness (Epworth Sleepiness Scale [ESS]) at 6 and 12 months in participants receiving DMF; To examine whether an association exists between fatigue and baseline demographics (e.g., age and sex) and disease characteristics (e.g., disease duration, baseline disease activity, treatment history, expanded disability status scale [EDSS] score, and PROs); To assess any changes in fatigue-related medication use.